In my attempts to find ways beyond breastfeeding to get BB settled to sleep, I've discovered that deep, exaggerated breathing helps to calm her down. Often I'll say, "Shhhh" on the exhalation, but not always. And as an extra benefit, the breathing helps bring me down a notch or two as well.
So far, it only works if I'm actually touching her, and it's rather difficult to do quality deep breathing while hunched over the portacrib. But it's good to have another possible tool to work with.
We've also stopped using the white noise and have replaced it with lullaby music. It had reached the point where I could hear every repeated, digitized pop, buzz, and pattern in the noise machine's recording, and it was driving me batty. I find it much easier to listen to Bobby McFerrin sing "Common Thread" over and over and over. And it's good music to breathe by.